I have had a love/ hate relationship with AMEX for near on 40 years. I started with a green charge in the late 80’s early 90’s. That eventually became a gold card, at some point it turned to Platinum. I have no idea how AMEX monitor spend, in 2007 I had called and asked if they would knock back a one off charge for approximately $150K (x3-5 my normal spend) I had to provide evidence I could facilitate the payment at month end which I did, the answer was we will approve. 2 months later I attempted to put through a single charge for $12K and it was knocked back, in the same month I was sent an invitation for the black card (centurion), go figure.